The plates made of ceramic, glass, stone, marble, granite, etc., have been used for some time now, for their placement on raised access floors, i.e. flooring supported on pins, pedestals, crossbars or the like, at a certain height from the concrete layer (natural floor), which enables the passage of mechanical and electrical services through the gap created between both floorings.
The problem with all these materials is that, when they are used in raised access floors, since they rest on pins at several support points, the remaining areas are suspended into the air, and the thickness thereof has to be considerably increased, so as to avoid breakages when these parts have to support loads or the traffic of persons or materials, as well as the deflection caused by the weight load.
This thickness increase entails, firstly, a significant weight increase, since in most cases the plates have to at least double their weight.
Moreover, the weight increase makes them very difficult to place, as a much greater effort is required to handle the materials and it further increases transport costs, since the volume they occupy is much larger than that of the parts having a normal thickness.
All this entails, in addition, an excessive consumption of raw materials.
Likewise, this thickness increase in many cases does not solve the breakage problem, particularly with regard to the impact strength and bending strength thereof.
To solve these problems, there are known solutions, which offer an alternative to the thickness increase, such as for example, the adhesion of calcium sulphate, chipboard panels, gypsum and cellulose fibers, among others, which adhered with a resin onto the back of the part, provide enough strength for the use thereof in raised floors.
Thus, for example, patent EP 2148023 A1 covers the possibility of reinforcing, by means of wood, cement or calcium sulphate or similar, supports such as ceramic, porcelain, stone or the like, for the use thereof in raised floors.
Furthermore, patent EP 1304425 A1 discloses the possibility of reinforcing stone materials with cores made of gypsum and cellulose fibers, indicating, as optimum thickness of the material-reinforcement assembly, 30.3 mm, of which 13.3 mm correspond to the reinforcement thickness.
Moreover, the Spanish patent ES 2258912 also covers the possibility of reinforcing stone materials by adhering one or more ceramic parts to the back of the stone using adhesives and resins.
Solutions such as sticking another similar part or of a different nature as a sandwich are also used, such that an indivisible assembly that improves the strength of the rigid material is obtained.
Accordingly, the invention patent ES 2154562 covers the possibility of adhering a ceramic part, the dimensions of which match the size of the stone material being thereby reinforced.
However, as in the case described at the beginning, these reinforcement materials significantly increase the weight of the material they reinforce. In the case of the materials most typically used, calcium sulphate, the weight is tripled relative to the weight of the rigid plate to be reinforced, or, in the case of the chipboard panel, the weight is doubled relative to the rigid material without that reinforcement. In the case of a part reinforced with another similar part adhered to the back thereof, the weight of the same also doubles.
The reinforcements used are, in addition, very thick. The reason for this thickness is to prevent, aside from the risk of breakage, the deflection problem when a static load is applied on the part being reinforced. According to standard UNE EN 12825, relative to Raised Access Floors, there are static loading requirements established that the parts have to meet for the use thereof in raised flooring. Under section “4.2.2.: Static loading requirements”, in table 2, the deflection limits are provided in mm, which, by no means, can be exceeded when applying loads onto the same.
There are other reinforcements for rigid parts, which thickness is very low, however in spite of providing high mechanical strength values, they cannot be used in raised floors. As matter of fact, these reinforcements are focused in reinforcing parts for floors or walls, which are intended for uses different to raised floors.
Specifically, as shown in patent ES 2160664, a reinforcement having a minimum thickness is achieved on a stone material, but has the disadvantage that it cannot be used in raised floors, since as indicated on page 4, lines 50 to 55, with a weight of 600 kg, the deflection of the reinforced part is 7 mm, which is outside the maximum limits allowed for this type of floors, which is 4 mm (such as prescribed by the Standard UNE EN 12825).
In addition, in document ES2160664, mat or mesh percentages above 50% are used, which has the disadvantage of, as it is necessary to use meshes that are very thick to achieve suitable mechanical properties, preventing the mesh from being embedded in the resin with just one application.
Therefore, a second resin application over the mesh would be necessary for the latter to be completely impregnated with the resin, which entails a greater investment, higher costs, a worse aesthetic aspect, etc. without thereby improving the mechanical properties of the material.
Another option in order to have a mesh percent above 50% completely embedded using one single application step, would be to use meshes that are less thick, but then there would be the drawback of not achieving the required mechanical properties.
Furthermore, patent PT 105013 A mentions a 2 mm thick cork reinforcement, for placing floors and walls and; in patent WO 2010/072704 A1, ceramic parts are reinforced with sheets of galvanized steel having a thickness between 0.1 and 1 mm, preferably between 0.3 and 0.5 mm; in both cases the breakage problem is not solved, particularly with regard to the impact strength and bending strength thereof.